What is Patenting?
The special heat treatment given to medium carbon, high carbon and low alloy steels wire rod is called patenting. The process consists of heating the material well above the austenitizing temperature to ensure formation of homogeneous austenite. After soaking for sufficient time at this temperature, the steel is quenched in a bath maintained at a constant temperature. For a given steel, the quenching bath temperature is kept in the vicinity of the nose of TTT curve i.e. 450-550C. This results in transformation of austenite to fine pearlite. Lead bath or salt baths are commonly used for quenching the steel. The process is mainly used for wires, ropes and springs.
